Multi‐geophysical approach for the better understanding and characterization of subsurface structures

Abstract

Understanding and characterizing subsurface structures is challenging, especially when the objective is to investigate sites for nuclear waste disposal. This paper presents a multi‐geophysical approach for subsurface experimental investigations in which seismic data are used to improve electrical resistivity tomography quality. Different synthetic models ranging from simple to complex were created to quantitatively demonstrate the improvements enabled by the use of this strategy. Moreover, the scheme was tested at Beishan, a candidate site for the disposal of high‐level radioactive waste in northwestern China. The results show that the combination of geophysical data sources improves the interpretation of the subsurface over a single source. The root‐mean‐square level and runtime were found to rapidly decrease when using the proposed scheme.

Complex conductivity of soils

“…The amplitude of resistivity and the phase can be recasted into a complex conductivity. Under an applied (primary) electrical field, its in-phase (real) component characterizes the electromigration of the charge carriers while its quadrature (out-of-phase, imaginary) component is used to describe local accumulations of electrical charge Induced polarization has many applications in hydrogeophysics including inference of hydraulic properties [Binley et al, 2005;Weller et al, 2010;Joseph et al, 2015;Nordsiek et al, 2015], facies discrimination , the detection of contaminants in soils [e.g., Sogade et al, 2006;Flores Orozco et al, 2012;Schwartz and Furman, 2012;Schmutz et al, 2012;Chen et al, 2013], and the detection of cracks [e.g., Okay et al, 2013]. Induced polarization has shown also a unique capability to monitor nonintrusively sorption processes in the electrical double layer [Vaudelet et al, 2011a[Vaudelet et al, , 2011bHao et al, 2016] and precipitation of metallic particles during redox-controlled reactions [e.g., Mewafy et al, 2013;Abdulsamad, 2017].…”

“…While much work has been done in describing the electrical conductivity of soils (see a review in Friedman [2005]), few publications have targeted the complex conductivity of these porous materials [see Schwartz and Furman, 2012;Nordsiek et al, 2015, for limited investigations with few core samples]. In the present paper, we test the dynamic Stern layer model developed by Revil and collaborators to describe the complex conductivity of brine-saturated clayey soils.…”

The effect of near‐surface azimuthal anisotropy on a joint interpretation of seismic and electrical resistivity data

“…Joint interpretation has * E-mail: yaskevichsv@gmail.com gained popularity in recent years for studying the near-surface as well as deeper subsurface structures (Carcione et al, 2007). Due to the different physics of the two phenomena, electrical resistivity and seismic data are rarely inverted simultaneously -the common approach is to use seismic horizons in electrical resistivity inversion as a structural factor (Alvarez et al, 2017) or as a prior model (Lu et al, 2016).…”